選取河北省2003年和2004年兩次較大的降雪過程，利用常規氣象資料和NCEP再分析資料，對它們的環流形勢和物理量場作了對比分析。結果表明，500 hPa南北兩支槽在110°E附近同位相疊加、地面氣壓場“北高南低”并在河套地區有倒槽生成是河北出現大（暴）雪的有利形勢。低層暖溫舌和暖平流的存在為大（暴）雪的形成提供了較好的熱力條件。槽前西南氣流、低層偏東氣流和低空急流都能為產生大（暴）雪帶來充足的水汽。高層輻散、低層輻合的水平散度結構和整層為垂直上升氣流的分布，加強了上空的抽吸作用，有利較大降雪的發生。而整層是正渦度（正垂直螺旋度）對垂直上升運動最有利。925 hPa和850 hPa溫度同時降至0 ℃以下，且地面氣溫小于等于1 ℃是適合降雪的溫度條件。
In order to reveal the development mechanisms of heavy snowfall in Hebei Province,two heave snow processes on 14 to 16 March 2003 and 20 to 21 February 2004 are selected. A contrast analysis of their meteorological characteristics is made from aspect of synoptic situation and physical mechanism by means of numerical diagnosis with the NCEP reanalysis data and conventional observation data. The results show that the combination of south and north troughs with identical phase around 110°E at 500 hPa, the allocation of the surface pressure field with high in north and low in south, and the appearance of the ground inverted trough in the Hetao area of NW China, as well as the thermodynamic conditions with warm temperature tongue and warm advection in the lower troposphere, are the favorable largescale background for the formation of heavy snowfall. There are three important paths of water vapor in the two snow events: from southwest in front of the 500 hPa trough, from east at low level, and from lowlevel jet. From the cross sections of vorticity, divergence, vertical velocity and vertical helicity, it is found that the vertical distribution of convergence at low level but divergence at upper level and ascending motion in the whole troposphere benefit the forming and maintaining of heavy snowfall, and the distribution of positive vorticity (vertical helicity) in the whole troposphere is most favorable. It is also suggested the temperature descending to below 0 ℃ at both 850 hPa and 925 hPa, meanwhile below 1 ℃ in the surface, is favorable to snowing. The results can be used as reference in the forecasting heavy snowfall.